Sewing machine

Abstract

An actuating mechanism is proposed for the hook and feed dog in a portable sewing machine of the type employed for sewing bags of jute, paper, and the like. In the proposed mechanism, a single cam determines both the compound movement of the hook, which is spring loaded against the cam and provided with at least one ball for reducing the frictional resistance, and of the feed dog by means of a connecting rod journalled at one end to a vertically adjustable support such as to allow the length of the seam stitch to be varied.

I claim: 
     
       1. A sewing machine of the type for making chain stitches, comprising a shrouding case,   a sewing needle,   a hook co-operating with said needle for making chain stitches,   a feed dog for feeding material to be sewn,   a driving motor,   a shaft rotated by said driving motor,   a cam on said shaft,   a supporting member for said hook, said supporting member pivotally supporting said hook about a first axis and being pivotally connected to said shrouding case about a second axis forming an angle with said first axis,     means for limiting pivotal movement of said hook with respect to said supporting member about said first axis, and   resilient means for constantly pushing said hook against said cam: wherein said cam has a peripheral profile for first displacing said hook about said first axis and then displacing said hook together with said supporting member about said second axis and vice versa, whereby said hook performs oscillations in two planes forming an angle between each other.   
     
     
       2. A sewing machine as claimed in claim 1, wherein said hook is supported by said supporting member about a first horizontal axis and said supporting member is pivotally connected to said shrouding case about a second vertical axis, and   wherein said means for limiting pivotal movement of said hook with respect to said supporting member about said first axis comprise an abutment on sais supporting member and an adjusting screw on said hook for engagement with said abutment.   
     
     
       3. A sewing machine as claimed in claim 1, wherein said supporting member comprises a disk having through bores therein extending substantially parallel to two opposite flat faces of said disk and defining said first and said second axis, respectively, and   wherein the machine further comprises a fixed support having spaced apart lugs for receiving a pivot pin penetrating one of said through bores and defining said second axis,   said means for limiting pivotal movement of said hook with respect to said supporting member about said first axis comprising an abutment on said hook engaging a corresponding one of said flat faces of said disk.   
     
     
       4. A sewing machine as claimed in claim 1, wherein said hook has a lug projecting laterally therefrom in a direction substantially parallel to said first axis, said lug defining seats for receiving balls engaging said peripheral profile of said cam. 
     
     
       5. A sew machine as claimed in claim 1, further comprising a connecting rod having one end eccentrically connected to said cam,   a connecting lever having one end pivotally connected to another end of said connecting rod,   a supporting arm having one end adjustably secured to said shrouding case and another end pivotally connected to another end of said connecting lever,   an arm integral with said feed dog and pivotally connected to said connecting rod at a point thereof between said one and said another end thereof, and   support means for pivotally supporting said feed dog on said shrouding case.   
     
     
       6. A sewing machine as claimed in claim 5, wherein said support means comprises a first C-like support pivotally connected to said feed dog about a substantially horizontal axis,   a supporting arm having one end pivotally connected to said C-like support about a substantially vertical axis,   and a further C-like support pivotally connected to another end of said supporting arm about a substantially vertical axis and pivotally supported by said shrouding case about a substantially horizontal axis.